Energy assessment of PCM/T system integrated with interior shading cells in building glass facades

This study experimentally investigates a hybrid passive-active building façade that combines phase change material (PCM) with an adjustable solar shading window to enhance indoor thermal comfort and recover useful thermal energy. The proposed window-integrated system incorporates RT-47 PCM and an active water circulation loop to extract stored heat. Two identical wooden test rooms (400 × 400 × 400 mm) were constructed and tested under real outdoor conditions in Mansoura, Egypt, during June 2025. One room was equipped with the PCM-based shading system, while the reference room used conventional clear glazing. The experimental campaign focused on evaluating the effects of inlet water velocity (0.005, 0.01, and 0.04 m/s) and shading tilt angle (0°, 30°, and 60°) on thermal performance. Results indicate that increasing the inlet water velocity significantly enhances heat transfer between the PCM and the circulating water. At the highest velocity of 0.04 m/s (Re = 380), the system achieved a maximum indoor air temperature reduction of 6 °C and recovered up to 823.7 W of thermal energy through the water loop. An economic assessment further demonstrated the feasibility of the proposed design, showing a substantial reduction in annual total cost (ATC) compared with the conventional room. After 10 years at a 4 % interest rate, the ATC decreased from 193.21 $/year to 13.51 $/year. Overall, the results highlight the strong potential of PCM-integrated adaptive shading systems with active heat recovery as an effective façade solution for low-energy buildings.